The land beneath the nation's capital bulged upward during the Ice Age — and now it's settling back down, putting the city at even greater risk of sea level rise.

Washington DC is sinking: It's not just a metaphor for a dysfunctional government anymore.

Scientists have known for a while that sea levels are going up faster along the US mid-Atlantic coast than globally. As it turns out, the water's not only rising, but a huge bulge of land — driven upward in the last Ice Age — is now settling slowly downward along the Eastern seaboard.

As a result, Washington and much of the surrounding Chesapeake Bay region is expected to sink by about six inches between now and 2100 as seas get higher, according to a study published this week.

"We're in relatively early stage in this process," geologist Ben DeJong, the study's lead author, told VICE News. "This will continue for the foreseeable future."

It's not yet time to put a big set of rubber boots on Thomas Jefferson, or attach pontoons to Lincoln's chair.

DeJong's research focused on the marshy Blackwater National Wildlife Refuge in Maryland, on the eastern shore of the bay. Using a combination of core samples from the ground and laser imagery from aircraft overhead, he and his co-authors from the University of Vermont and the US Geological Survey were able to track how the land warped upward ahead of the glaciers, which reached as far as present-day New Jersey more than 20,000 years ago — and is gradually settling back now.

"What's kind of cool about this is it gives us a nice solid benchmark — a value of relative sea-level rise that we can pretty confidently hang our hat on," DeJong said. "At the very least, we have sort of a baseline value that we can superimpose on any of our estimates for sea-level rise based on climate scenarios."

That bulge not only includes the Washington area, it reaches southward as far as North Carolina, he said. The study appeared in an American scholarly journal, the Geological Society of America Bulletin.

It's not yet time to put a big set of rubber boots on Thomas Jefferson, or attach pontoons to Lincoln's chair. But it's one more thing planners will have to take into account in when planning to manage climate change in a city where sea levels are projected to rise as much as 15 inches by mid-century at current rates.

At that point, Washington — which sits more than 100 miles up the Potomac River from Chesapeake Bay — be faced with a minimum of $2 billion in real-estate losses, not counting infrastructure, monuments, and military installations like the Washington Navy Yard, a 2012 study by University of Maryland researchers found.

It's a problem that's already being seen around Norfolk, Virginia, where "double whammy" of sinking land and rising seas is eating away at the world's largest naval base, retired Navy captain Ray Toll told VICE News.

"Any garden-variety thunderstorm hits here, and your streets are flooded,"said Toll, who's now the director ofCoastal Resilience Research at Virginia's Old Dominion University. Right now, the federal government and communities along that stretch of coast are trying to figure out how to limit the worst damage and adapt to what's coming, and he called DeJong's research "a welcome study."

"We know we have a lot of uncertainties in the science and engineering because of the data inadequacies and the models," he said. "We don't have a whole lot of time, but we do have time to think though this in a deliberate way."

And Zoe Johnson, the climate change coordinator for the multi-agency Chesapeake Bay Program, told VICE News that DeJong's study bolsters what her organization has been seeing from its measurements.

Maryland's coast is could see nearly a foot and a half of sea-level rise by 2050 and possibly 4 feet or more by 2100, the commission noted in a climate-change plan released earlier this year. About 580 acres of land a year is being washed away, Johnson said. Islands that once had homes on them have slipped beneath the waves, and Baltimore and Annapolis have seen a nine-fold increase in low-lying streets being flooded, she added.